Botulinum toxin A poisoning by local aesthetic injection: clinical and electrophysiological analyses of 20 cases

Objective To observe the clinical and electrophysiological characteristics of botulinum toxin A poisoning induced by local cosmetic injection, and to explore the possible pathogenesis. Methods Clinical data of 20 patients with botulinum toxin type A local cosmetic injection poisoning admitted to our hospital from January 2016 to December 2018 were collected and electrophysiological tests were carried out. Results The clinical manifestations of 20 patients were mainly 15/20 (75.0%) with limb weakness, and the proximal end was heavier than the distal 20/20 (100%), and the upper limb was heavier than the lower limb 26/20 (80%), followed by dysphagia 12/20 (60%), dysarthria 5/20 (25%), cervical muscle weakness 5/20 (25%), extraocular muscle paralysis 4/20 (20%), masseter muscle weakness 3/20 (15%) and respiratory muscle weakness 2/20 (5.0%) with respiratory failure 1/20 (5.0%). The results of neurophysiological examination showed the highest rate of SFEMG (90.0%), followed by RNS (80.0%), EMG (65.0%) and NCV (40.0%), suggesting that neuromuscular junction dysfunction was the main presentation. Patients who actively gave botulinum antitoxin injection therapy and symptomatic support treatment had good prognosis. Conclusions Local cosmetic injection of botulinum toxin type A may lead to poisoning. The symptoms of poisoning are mainly caused by limb weakness. Neuroelectrophysiological examination can assist in the diagnosis of botulinum toxin poisoning. Key words: Botulinum toxins, type A; Botulinum antitoxin; Injections; Electrophysiology